The present invention relates to a method and an apparatus for producing a magnetically anisotropic Nd-Fe-B magnet material having large coercive force and magnetic energy product by compressing a green body and treating it to have magnetic anisotropy, the green body being obtained by cold forming of flakes or powders obtained by pulverizing an Nd-Fe-B magnetic ribbon formed by a rapid quenching method.
It is conventionally known as disclosed in Japanese Patent Publication No. 61-34242 to produce an Nd-Fe-B sintered magnet by preparing an ingot by melting a mixture of Nd, Fe, B and if necessary additional elements, pulverizing it to form powder, sintering and heat-treating it. Further, it is known that an Nd-Fe-B magnet can be provided with a high coercive force by making the crystal grains of the magnet finer, for instance, to an average grain size of about 0.01-0.5 .mu.m. This fine crystal-type Nd-Fe-B magnet is disclosed, for instance, in Japanese Patent Laid-Open No. 60-100402. It is also disclosed that die upsetting can provide the magnet with magnetic anisotropy, but it is not disclosed how a pressed powder body having fine crystal grains can be efficiently formed into a compressed body with magnetic anisotropy, and what deformation by upsetting can increase the magnetic properties of the compressed body.